When you mention using a long lasting high value treat to throw in the opposite direction so we can get whatever it is she is chewing on, I am just concerned that we will be on this never ending train of trying to find something better than what she has. Is it okay to give her something that is still higher in value but is not as long lasting?
Well, the purpose is to create a strong impression that we are the providers of great things, and that if we need to take away, we offer something that is far better. For sake of an example, back to eating out, imagine you are at a restaurant complaining about a steak not being as rare as you hoped for. The waiter apologizes, takes your steak away and returns with a much smaller steak albeit it's rare as you hoped. You may say nothing at first, but you may feel disappointed. If this happens often enough, a day may come when you may have had enough and get angry or stop dining there.
I say this because after some time, if the trade isn't fair enough, the dog may come to learn that it's not worthy giving up the long-lasting chew and the dog at some point may instinctively move towards the treat and then make a sudden about face and decide to go back for the long-lasting chew with the risk of biting if you're right about to pick it up.
So I call it the art of "fair trading". It may sound complicated but it really isn't. Like if your dog chews on something, you can have something higher in value that can last somewhat long versus gobbled up in a second always ready so that you can swap. If a dog is chewing a shoe that isn't edible by any way, you can even swap that for a dog treat that you can cut up in various pieces so that your dog has to go on a little treasure hunt which adds durability and gives you time to retrieve the swapped item. Of course, it also helps to keep things that a dog isn't supposed to chew out of the way, so that we don't have to swap too often 😉
Yup, until she is more trustworthy, keeping separated when your nephew is over is the best approach. We don't want any accidents to happen.